Prevalence of Frailty in Mild to Moderate Alzheimer's Disease: A Systematic Review and Meta-analysis

Background: Frailty is a state of increased vulnerability to poor resolution of homeostasis as a consequence of age-related decreased physiological reserves. Although physical frailty and cognitive impairment have been shown to be associated, evidence on the prevalence of frailty in Alzheimer's disease is scarce. Objective: To conduct a systematic review on the prevalence of frailty and to combine the data to synthesize the pooled prevalence of physical frailty among patients with Alzheimer's disease. Method: Five electronic databases (Embase, MEDLINE, CINAHL Plus, PsycINFO, and the Cochrane Library) were searched for studies providing cross-sectional data on physical frailty among patients with Alzheimer's disease published from 2000 to January 2016. Results: Of 2,564 studies identified through the systematic review, five studies incorporating 534 patients with Alzheimer's disease were included for the meta-analysis. The prevalence of frailty varied with a wide range from 11.1% to 50.0% and the pooled prevalence was 31.9% (five studies, 95% confidence interval (CI)=15.7%-48.5%). The high degree of heterogeneity was observed in all analyses. A borderline publication bias was detected. Conclusion: The current study showed that frailty is highly prevalent in older patients with Alzheimer's disease in the community with the pooled prevalence of 31.9%. The true prevalence may be much higher given that end-stage patients may not be included. This information is important for clinicians and researchers.